How much space do you need for a Märklin C track layout?

Benjamin | TrackDrawer.com · published 30 October 2026

For a closed loop of Märklin C track you need a baseboard of at least 90 x 90 cm: a circle of twelve R1 curves. If you want an oval with a passing loop, allow at least 160 x 90 cm. On 180 x 90 cm a station with sidings already fits, on 200 x 120 cm a double track with a yard.

These figures are not guesses. We measured them with the TrackDrawer Auto-designer, using an ordinary stock of C track and a 5 cm clear edge around the board. Below you can read how they come about and what they mean for your room.

Why C track takes more room than you think

Märklin C track is H0 track with a gauge of 16.5 mm and a fixed roadbed. Seen from above, that roadbed is 40 mm wide. It sounds like little, but it counts on both sides of the line: the outer edge of a curve lies 20 mm further out than the centre line of the track.

The smallest curve radius of C track is R1 at 360 mm, measured to the track centre. Each next radius lies 77.5 mm further out. That is exactly the track spacing of C track, so R1 and R2 together form a double track.

Outside size of a circle per radius

A full circle sets the depth of every layout: an oval is nothing more than a circle cut open and stretched with straights. So first the outside size per radius.

The outside size is twice the radius plus the roadbed width of 40 mm. For the board we add 2 x 50 mm of clear edge, so the track does not run right up to the edge and a derailing train does not fall off straight away.

Measured with the Auto-designer in steps of 5 cm, that gives a 90 x 90 cm board for R1: 86 cm is the calculated minimum, and with 5 cm less (85 cm) no closed loop fits. That smallest loop consists of twelve R1 curves of 30 degrees, 2.26 m of track in total.

A circle is a very short run, though. In practice you want at least an oval.

An oval: from 100 x 90 cm

Put straights between the two half circles and the board gets wider, not deeper. On 100 x 90 cm the Auto-designer lays an R1 oval with 16 pieces and 2.53 m of track. Nothing more fits at that size: besides the oval the designer only finds the smallest closed loop. There is no room for a turnout.

At 90 cm depth you are therefore tied to R1. If you want R2 as the outer curve, the table says you need at least 1015 mm of depth, in practice a board a little over 100 cm deep.

An oval with a passing loop: from 160 x 90 cm

A passing loop turns a simple circuit into a layout where trains can cross each other. You need two turnouts for it, plus a reverse curve to bring the second track parallel again. The standard C track turnout (24611 left, 24612 right) is 188.3 mm long and diverges on R2 over 24.3 degrees. With the reverse curve 24224 the second track ends up 77.5 mm beside the first.

That costs width. The Auto-designer finds the first loop with a passing track on 160 x 90 cm: "Station with two platforms on R1, plus 2 sidings", with 31 pieces and 5.32 m of track. At 155 cm wide it no longer works. Even at 100 cm deep, 160 cm stays the smallest width: the extra 10 cm of depth does not give a shorter board here.

What fits on common sizes?

For a few common baseboard sizes we checked which variants the Auto-designer lays with the same stock of C track.

A few things stand out. On 180 x 90 cm, a popular size for a first H0 board, you can already choose between a circuit with a passing loop, a small station with sidings and a yard. Read an H0 layout on 180 x 90 cm to see what each of those variants offers.

The step to 200 x 120 cm is bigger than the extra 20 cm of width suggests. The extra 30 cm of depth makes room for R2 and R3, and with them a double track all the way round. Track length goes from just over 6.5 m to almost 11 m. A dogbone on R2 gives a long run with two turning points in the curves on the same board.

R1 or a larger radius?

R1 is the smallest radius and therefore the space saver. Long coaches and some locomotives look less good in a tight curve, and the body swings out further. So check the minimum radius the manufacturer states for your stock.

As a rule of thumb: every step to a larger radius costs 15.5 cm of extra depth (2 x 77.5 mm). From R1 to R3 that is 31 cm. If you want to show wide curves, a slightly deeper board often gains you more than extra width.

Thinking about the rest of the room

The board size is not the whole room. You also need to reach the layout: re-railing a train, freeing a turnout, cleaning track. With a board against a wall, a reach of about 60 to 70 cm is the most you can comfortably manage to the back. At 120 cm deep you therefore need access from two sides, or a plan where the back needs little attention.

A board you store away (under the bed or against the wall) should not get too heavy or too big either. Two boards of 90 x 90 cm side by side give 180 x 90 cm and are easier to carry.

Frequently asked questions

Can I build a C track layout on an 80 x 80 cm board?

Not with a closed loop of standard C track. The smallest circle, with R1, is 76 cm wide across the outside of the roadbed. With a 5 cm edge all round you need 86 cm, measured with the Auto-designer a board of 90 x 90 cm.

How much depth do I need for a double track all the way round?

With R1 inside and R2 outside, R2 sets the depth: 915 mm outside size, just over 1 m with an edge. On 200 x 120 cm the designer lays a double track in R2 and R3.

Try your own board

Browse the C track plans in the Railfolio for ideas on different sizes. Then enter your own board and your own stock, and let the Auto-designer lay out a plan that really fits.